In potato processing operations such as used in the dehydration of potatoes, water flows through various cookers, pre-cookers, blanchers, and transport systems. The overflow or effluent water from such processing operations is called potato wastewater or potato water. Such potato wastewater is difficult to filter due to dissolved starch which tends to block screens in the filtration equipment. Various regulatory agencies are instituting stricter standards for the disposal of such wastewater. Accordingly, there is a need to reduce the potato solids in such wastewater and to recover the solids as a usable byproduct.
One potato wastewater treatment method for this purpose is disclosed in Ferro, et al. U.S. Pat. No. 6,555,003 (the '003 patent). There, the wastewater stream is treated with an alpha amylase enzyme to hydrolyze starch in the wastewater followed by ultra-filtration of the enzyme-treated wastewater to filter and remove suspended solids in a first concentrate stream followed by reverse osmosis-filtering of the ultra-filter permeate. However, there are disadvantages with the presence of the enzymes as an impurity in the concentrate for certain uses. Further, the most efficient use of certain enzymes may require the energy cost of heating the wastewater to the optimum effective range for the enzyme.
Another approach to the recovery of protein from potato wastewater streams is described in Gonzalez, J. M., et al., Food Hydrocolloids, Vol. 4, No. 5, pp 355-363, 1991. There, a hydrocolloid, specifically carboxy methyl cellulose (CMC), is stated to be used as a complexing agent. That paper also describes the use of pH adjustment and an added electrolyte which it states to be inferior to the use of CMC in that it is stated to be difficult to separate coagulated protein due to low sedimentation rates and poor filter ability.
Thus, there is a need to reduce the potato solids in potato wastewater and to recover the solids as a usable byproduct, particularly one useful as an ingredient for foods for human, animal, or microbiological consumption.
It is an objective of the invention to provide a method for treating potato wastewater and to provide a byproduct of such treatment suitable for use as an ingredient for food for human, animal, or microbiological consumption.